1. Field of the Invention
This invention relates generally to semiconductor processing, and more particularly to an apparatus for and method of inspection using entangled particle beams.
2. Description of the Related Art
Accurate and reliable defect inspection is vital to successful semiconductor fabrication. Microelectronic circuit structures may be highly sensitive to perturbations in the myriad of process steps that must be performed in their fabrication. For example, particulate contamination introduced by various semiconductor processing tools and unwanted residual films left over after various semiconductor processing steps can lead to device performance issues or require wafer scrap. Most semiconductor chip fabrication techniques involve the sequential application of films of various composition on a silicon wafer or substrate. The successful application of the various films on top of each other often requires a relatively pristine underlying surface upon which the next formed layer is formed. However, the presence of an unwanted residual film on the underlying layer may cause the overlying film to later delaminate and lead to device failure.
Conventional optical microscopy as a means of inspection is rapidly approaching the available limits of resolution for microelectronic devices. Conventional means of improving resolution including obtaining a higher numerical aperture, and shorter light wavelengths must still address diffraction limits as well as the high cost of larger lenses and higher frequency light sources for such upgraded imaging systems. For example, if it is desired to use light below a wavelength of about 180 nm, then complex vacuum systems must typically be employed since air does not transmit light well at wavelengths below 180 nm.
Another conventional means of optical imaging for microelectronic structures involves near field scanning optical microscopy (xe2x80x9cNSOMxe2x80x9d). NSOM systems can achieve high resolution but at the expense of a very small field of view since the probe tip for such systems entail a very small aperture that is placed extremely close to the surface to be imaged. These types of NSOM systems are typically not practical for most finished integrated circuits where the layer of interest to be imaged may be buried under a passivation layer or a substrate in the case of back side imaging.
The present invention is directed to overcoming or reducing the effects of one or more of the foregoing disadvantages.
In accordance with one aspect of the present invention, a method of inspection is provided that includes generating an entangled set of particle beams and directing one of the entangled set of particle beams to a location of a workpiece. One of the entangled set of particle beams interacts with the location of the workpiece. One of the entangled set of particle beams is observed after the interaction with the location of the workpiece to inspect the location of the workpiece.
In accordance with another aspect of the present invention, a method of inspection is provided that includes generating a plurality of pairs of entangled photons. The plurality of pairs of entangled photons is divided into a first beam and a second beam. One of the first and second beams is directed to a location of a workpiece such that it interacts with the location of the workpiece. One of the first and second beams is observed after the interaction with the location of the workpiece to inspect the location of the workpiece.
In accordance with another aspect of the present invention, an inspection device is provided that includes a radiation source capable of transmitting an incident beam, a nonlinear member for producing a set of entangled beams from the incident beam, and an imaging device for observing an interaction of one of the set of entangled beams with a location of a workpiece.
In accordance with another aspect of the present invention, an inspection device is provided that includes a radiation source capable of transmitting an incident beam and a nonlinear crystal for producing a plurality of pairs of entangled photons from the incident beam. The plurality of pairs of entangled photons is divided into a first beam and a second beam. An imaging device is provided for observing an interaction of one of the first and second beams with a location of a semiconductor workpiece.